The present disclosure relates to bone plates, screws and other fasteners, and related instruments. Examples include a screw and washer system with instruments, polyaxial screw and plate systems, bone clamp systems with spacers, sleeves, and/or cages, multi-level bone clamp systems, minimally invasive bone clamp systems, motion preserving systems, and instruments for handling plates, applying compression, and applying locking forces. More specifically, the present disclosure is set forth in the context of spinal surgery, such as spine fusion or motion preservation.